1. Technical Field
The present invention relates to wireless communications and, more particularly, to high-throughput frames for low-rate transmission environment.
2. Related Art
Communication systems are known to support wireless and wire lined communications between wireless and/or wire lined communication devices. Such communication systems range from national and/or international cellular telephone systems to the Internet to point-to-point in-home wireless networks. Each type of communication system is constructed, and hence operates, in accordance with one or more communication standards. For instance, wireless communication systems may operate in accordance with one or more standards, including, but not limited to, IEEE 802.11, Bluetooth, advanced mobile phone services (“AMPS”), digital AMPS, global system for mobile communications (“GSM”), code division multiple access (“CDMA”), local multi-point distribution systems (“LMDS”), multi-channel-multi-point distribution systems (“MMDS”), and/or variations thereof.
Depending on the type of wireless communication system, a wireless communication device, such as a cellular telephone, two-way radio, personal digital assistant (“PDA”), personal computer (“PC”), laptop computer, home entertainment equipment, et cetera. communicates directly or indirectly with other wireless communication devices. For direct communications (also known as point-to-point communications), the participating wireless communication devices tune their receivers and transmitters to the same channel or channels (for example, one of a plurality of radio frequency (“RF”) carriers of the wireless communication system) and communicate over that channel(s). For indirect wireless communications, each wireless communication device communicates directly with an associated base station (for example, for cellular services) and/or an associated access point (for example, for an in-home or in-building wireless network) via an assigned channel. To complete a communication connection between the wireless communication devices, the associated base stations and/or associated access points communicate with each other directly, via a system controller, via a public switch telephone network (“PSTN”), via the Internet, and/or via some other wide area network.
Each wireless communication device includes a built-in radio transceiver (that is, receiver and transmitter) or is coupled to an associated radio transceiver (for example, a station for in-home and/or in-building wireless communication networks, RF modem, etc.). As is known, the transmitter includes a data modulation stage, one or more intermediate frequency stages, and a power amplifier stage. The data modulation stage converts raw data into baseband signals in accordance with the particular wireless communication standard. The one or more intermediate frequency stages mix the baseband signals with one or more local oscillations to produce RF signals. The power amplifier stage amplifies the RF signals prior to transmission via an antenna.
Typically, the data modulation stage is implemented on a baseband processor chip, while the intermediate frequency (“IF”) stages and power amplifier stage are implemented on a separate radio processor chip. Historically, radio integrated circuits have been designed using bi-polar circuitry, allowing for large signal swings and linear transmitter component behavior. Therefore, many legacy baseband processors employ analog interfaces that communicate analog signals to and from the radio processor.
One problem is increasing data throughput of a system under low-quality, or unfavorable, channel conditions. Under favorable channel conditions, higher, yet less robust, modulation transmission rates are used to transmit high-throughput frames. The higher modulation transmission rates generally have a multi-bit transmission capacity that allows more information to be transmitted within a given time span. Under low-quality channel conditions, a more robust, but slower modulation rate is used to improve the error rate that would increase using a higher modulation transmission rate. But the lower modulation transmission rates do not have multi-bit transmission capability, yet the additional information needed for the high-throughput frame needs to be conveyed with minimal processing overhead. Proposed techniques had been to statically increase the frame structure size. The increases, however, correspond to processing overhead increases under both low-quality and higher quality channel conditions. What is needed, therefore, is a technique to adjust a high-throughput frame based on the channel quality in wireless communication systems.